Refrigerator control



Feb. 3, 1953 c. s. GRIMSHAW 2,627,561

REFRIGERATOR CONTROL Filed Dec. 28, 1950 2 SHEETSSHEET 2 Inventor: Charles S. Grimsnaw,

His Attorney.

Patented Feb. 3, 1953 REFREGERATOR CONTROL Charles S. Grimshaw, Eric, Pa, assignor to General Electric Company, a corporation of New York Application December 28-, 195i), Scrial'Nc. 2D3,1'B6

(Ci. Nil-83.)

16 Claims.

My invention relates to refrigerator controls and more particularly to such controls incorporating a defrost setting.

In many household refrigerators an evaporator used for cooling the food storage compartment is exposed to the air in the compartment and, since the evaporator operates substantially below the freezing temperature of water, moisture condenses on the evaporator and collects in the form of frost. In order to operate the refrigerating apparatus at a relatively high efficiency it is necessary to remove this frost from time to time. To accomplish this the refrigerator control may be provided with an arrangement for manually or automatically effecting an increased evaporator temperature at intervals. For normal operating conditions it is also desirable to provide for adjustment of the normal temperature setting so that the operating temperature of the evaporator can be properly varied under diiierent operating conditions. However, it is usually desirable to establish some predetermined maximum temperature for the evaporator during the defrosting operation and it is desirable that the adjustment of the normal temperature setting not alfect the defrosting temperature. In other words, it is advantageous to have the evaporator rise to the same maximum temperature during defrosting regardless of the particular normal temperature setting being employed at the time of defrosting. In many refrigerator controls an adjustable biasing spring is provided for securing the adjustable temperature during normal operating conditions and a second spring is employed-for providing an additional opposing force which causes an increase in the evaporator temperature for defrosting, the biasing forces of the springs being added so that any variation in the normal temperature setting also afiects the defrost temperature. By my arrangement two independent springs are provided so that one spring is effective during normal operating conditions and the other spring only is effective during defrosting conditions, and

I have provided for the independent operation of these springs in a compact and simplified structure.

It is an object of my invention to provide a refrigerator control having a normal temperature control and a defrost control including an improved arrangement for rendering the defrost .1

temperature independent of the normal temperature control.

It is another object of my invention to provide an arrangement for automatically initiating defrosting including an improved arrangement for 2 rendering the defrost temperature independent of any changesin thenormal temperaturesetting.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention, a refrigerator control is employed which includes a conventional temperature-responsive element or bellows, a conventional adjustable spring opposmg the bellows, and a conventional snap-acting switch. In lieu of a single pivoted arm which is acted upon by the bellows and the opposing spring, I provide two parallel pivoted arms one of which is engaged by the spring and the other by the bellows. In addition, a second spring is provided between the parallel arms opposing movement of the arms toward each other. Dur ing normal operation the two arms move as a unit and the operation of this switch is the same as if a single arm were employed. To accomplish defrosting a stop is arranged to function for limiting the movement of the second arm and rendering the first spring ineffective. Under these conditions the second arm is moved by the bellows against the bias of the second spring only for ultimate actuation of the switch.

For a better understanding of my invention reference may be had to the accompanying dravings in which Fig. 1 illustrates a refrigerator control including an embodiment of my invention; Fig. 2 is a similar view of a modified form of my invention; and Fig. 3 is a view of a portion of Fig. 2 showing the control in a different position.

Referring to Fig. 1, there is shown a control which includes a housing 1 upon which is mounted a temperature-responsive element or bellows 2.

The expansion and contraction of the bellows 2 is effected in response to the temperature registered by bulb (not shown) mounted on an evaporator (also not shown) and connected to the bellows by a tube 3. A switch 4 is provided within the housing I the switch including a stationary contact 5 and a movable contact 6 for controlling the circuit of a refrigerating unit motor in a conventional manner.

A switch-actuating structure 1 is provided for transmitting movement of the bellows 2 to effect opening and closing of the switch 4. The switch actuating structure 1 is biased for normal operating conditions by a spring 8. One end of the spring 8 engages a cup 9 and a threaded rod I0 is arranged in threaded engagement with the tion, stopping operation of the refrigerating unit. Each time the bellows expands in the manner described and the arm I2 moves to the right, the pawl 43 also moves to the right to engage the next rearward tooth of the ratchet wheel 35. As the bellows then contracts during the other portion of the operating cycle, the arm l2 and the pawl 43 move to the left, thereby rotating the ratchet wheel 36 one tooth in a clockwise direction. This advances the stop 34 by the amount of one tooth in a clockwise direction.

After a predetermined number of cycles of operation of the refrigerating unit, or, in other words. after a predetermined number of complete operations of the control, the stop 34 is advanced to the dotted line position shown wherein it is aligned with the end 35 of the arm 24. As the bellows 2 thereafter expands during the warming up of the evaporator, the end 35 of the arm 24 encounters the stop 34, thereby limiting the move ment of the arm 24. This also renders the spring 3 ineffective, since the spring 8 bears against the immobilized arm 24. Continued expansion of the bellows 2 thereafter moves the arm [2 against the bias of the spring 21, and the maximum temperature of the evaporator which is required to move the arm [2 to the overcenter position of the spring 29 and to close the switch t is determined by the bias of the spring 21, and is independent of the immobilized spring a. The spring 21 is chosen so that it will require a greater pressure in bellows 2 to compress spring 2'! than spring 8. Accordingly, under these conditions, the evaporator must rise to a predetermined temperature which exceeds the maximum temperature reached during normal operating conditions before the arm 12 is moved sufficiently to close the switch 4. The maximum evaporator temperature determined by the bias of the spring '21 is chosen so as to effect a complete melting of the frost from the evaporator, and is independent of the setting of the spring 8. At the end of the defrosting period, the ratchet wheel 36 is advanced one more tooth, thereby positioning the stop 34 beyond the end 35 of the arm 24 and returning the control to its normal operating condition.

Summarizing, it can be seen that by the ar rangement shown the normal temperature conditions are determined by the setting of the lrnob I l and the resultant bias of the spring 8, this spring alone opposing movement of the switch actuating structure during the normal operating conditions. On the other hand, during defrost conditions, the spring 3 is rendered ineffective because of the positioning of the stop 34 in line with the end 35 of the arm 24, the maximum temperature is determined by the spring El independently oi the spring 8. Thus, the normal operating temperatures of the evaporator can be varied by adjusting the knob l l, but such ad- .iustrnent has no effect on the maximum temperature reached during the defrosting period. Although, for purposes of illustration, an automatic defrosting mechanism has been shown, it will be apparent that my invention could be carried out equally well by manually positioning a stop to limit the movement of the arm 24 for defrosting.

In Figs. 2 and 3, there is shown a modified form of my invention which also employs a stop effective under defrosting conditions for limiting the movement of the second arm so that the main spring is rendered ineffective and opposition to the expansion of the bellows is provided by an independent defrosting spring. The modified form differs from that shown in Fig. 1 in that a rotatable cam is provided for varying the position of the movable switch arm in its open position and thereby varying the amount of expansion of the bellows necessary to effect a closing of the switch. The same numerals have been employed to designate corresponding parts in Figs. 2 and 3 and in Fig. 1.

Referring now to Figs. 2 and 3, the control there illustrated includes a movable arm 12' corresponding to the arm 12 of the control of Fig. l. and a second arm 24' corresponding to the arm 2 of the form shown in Fig. 1. One end 24a of the arm 24 is received within an opening in the arm 12, the two arms [2' and 24' forming a unitary switch-actuating structure. As in the form previously described, an adjustable spring 3 bears against the arm 24 for opposing the bellows 2 during normal operation. The spring 2?, adapted to be brought into play under defrost conditions, is arranged between the arms l2 and 2 2- and en gages these arms. As illustrated, the spring 23 does not directly engage the arm 24 but it may be regarded as engaging the arm 24 since the dished member 30 and screw 35 may be considered part of the arm 24 and, moreover, these last-named parts may be omitted if adjustment of the spring is not desired. Relative movement of the arms l2 and 2d away from each other is limited by a stop 32 which is similar to the stop 32 of the form of Fig. l.

The movable switch arm or member It which corresponds to the member 13 in the form of Fig. 1, includes a laterally extending leg 6?, adapted to engage the periphery of a cam or rotatable member 4'! which is supported on a bracket 41a mounted on the housing I The en gagement of the leg 46 with the cam or disk :2? determines the position of the switch arm i8 and the movable contact 5 in the open position of the switch 4 and thereby determines the amount of movement of the arm l2 and hence the amount of expansion of the bellows 2 necessary to effect a closing of the switch, This is true since the closing of the switch is effected when the pivot point ll of the U-shaped element It moves past the point 43 at which the end of the overcenter spring 20 is connected to the car 22 of the arm 18'. Hence, variation in the position of the point 43, as determined by the engagement of the leg 46 with the cam 47, is effective to vary the temperature at which the switch 4 is closed. This characteristic is employed in the form of 2 and 3 for effecting defrosting.

The change in position of the switch arm it and the point 48 is achieved by forming the cam d? with a recess 49 in the periphery thereof. To effect defrosting by requiring a greater expansion of the bellows 12 before closing of the switch 4, the cam 41 is rotated so as to position the recess 49 in line with the leg 45, as shown in Fig. 3, the distance between. the pivot point i? of the U-shaped element H3 and the point 43 in Fig. 3 is greater than in Fig. 2 and hence a greater movement of the arm l2 and of the bellows 2 is required before the spring til passes over center to cause closing of the switch 4. By way of illus tra-tion, the cam 41 has been shown as moved by a mechanism which includes an actuating pawl 5i! and a retaining pawl i l acting on a ratchet wheel 35 for rotating the earn 4?; however, within the scope of this invention, any suitable arrangement, including manual rotation, may be As can be seen by comparing Figs. 2 andemployed for rotating the cam 47 to position this cam for defrosting;

The variation in the required movement of the arm i2 is employed as afactor in rendering the spring 3 ineffective and the spring 27 effective under defrosting conditions. The arm M includes a portion or leg 52 which is aligned with a stop 53 formed on the housing 1. The relationship of the leg 52 to the stop 53 under normal operating conditions is such that the leg 52 falls just short of contacting the stop 53 by the time the point I! passes the point 58 and the spring 29 shifts over center to close the switch 6. Hence, the arms l2 and 24' move as a unitary structure and the force opposing the expansion of the bellows 2 is provided by the spring 8. On the other hand when the cam 51 has been moved to the position as shown in Fig. 3, allowing the additional movement of the switch arm E8 in the open posi tion of the switch 4, the additional travel of the arm I2" effects engagement of the leg 52 of the arm 24 with the stop 53, further movement of the arm 24' being thereafter prevented. As in the form previously described, this limiting of the movement of the arm 24' renders the spring 8 ineffective. The subsequent movement of the arm l2 required to move the spring 20 over center and close the switch 4 is thereafter a move ment of the arm [2' relative to the arm 24' and hence is a movement opposed by the spring 2?. Therefore, under the defrosting conditions, the movement of the bellows 2 to effect closing of the switch 4 is opposed by the spring 21 and is independent of the spring 3. Accordingly, the temperature at which the switch 4 closes is determined by the setting of the spring 27 and this maximum defrost temperature is independent of any changes in the compression of the spring 8 which may result from adjustments of a. normal temperature setting by the knob I i.

Summarizing, with the arrangement shown in Figs. 2 and 3, the position of the cam i? affects the position of the switch arm I8 and it leg 35 in the open position of the switch. This change in the position of the switch arm 43' varies the distance between the points I? and it, as indicated by a comparison of Figs. 2 and 3, and hence varies the distance which the arm I? must be moved by the expansion of the bellows in order to effect an over center movement of the spring 2t and a closing of the switch 4. Moreover, the amount of travel required by the arm 52' under normal conditions, as illustrated in-Fig, 2, to close the switch 4 is such that the leg 52 of the arm 25 does not engage the stop 53. On the other hand, under the defrost conditions illustrated in Fig. 3, the stop 53 is effective to engage the leg 52 because of the increased travel'of the arm 12 and arm 24', rendering the spring 8 ineffective, and introducing the spring 27 as the sole force opposing the expansion of the bellows because of the relative movement thereafter of the arms l2, and 24.

While I have shown and described specific'embodiments of my invention, I do not desire my invention to be limited to the particular constructions shown and described and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A refrigerator control including a first movable arm, a temperature-responsive element for moving said first arm, a switch actuated by said arm at a predetermined temperature, a second movable arm, means engaging said second arm for opposing said temperature-responsive ele ment, a spring between said two arms and engaging said arms for normally maintaining said arms in spaced relationship, and a stop arranged to function for limiting the movement of said second arm whereby said tem-perature-responsive element moves said first arm relative to said second arm against the bias of said spring effecting defrosting.

2. A refrigerator control including a first movable arm, a temperature-responsive element for moving said first arm, a switch actuated by said arm at a predetermined temperature, a second movable arm, means engaging said second arm for opposing said temperature-responsive element, said means being adjustable for varying the temperature at which said switch is actuated. a spring between said two arms and engaging said arms for normally maintaining said arms in spaced relationship, and a stop arranged to function for limiting the movement of said sec ond arm whereby said temperature-responsive element moves said first arm relative to said sec ond arm against the bias of said spring for effecting defrosting.

V 8. A refrigerator control including a movable arm, a temperature-responsive element for moving said arm, a switch actuated by said arm at a predetermined temperature, a second movable arm, means engaging said second arm for opposing said temperature-responsive element, a spring between said two arms and engaging said arms for normally maintaining said arms in spaced relationship, and a stop movable to a position in the path of said second arm for limiting the movement thereof whereby said temperature-responsive element moves said first arm relative to said second armagainst the bias of said spring for effecting defrosting.

4. A refrigerator control including a movable arm, a temperature-responsive element for moving said arm, a switch actuated by said arm at a predetermined temperature, a second movable arm, means engaging said second arm for opposing said temperature-responsive element, said means being adjustable for varying the tempera ture at which said switch is actuated, a sprin between said two arms and engaging said arms for normally maintaining said arms in spaced relationship, and a stop movable to a position in the path of said second arm for limiting the movement thereof whereby said temperatureresponsive element moves said first arm relative to said second arm against the bias of said spring for effecting defrosting.

5. A refrigerator control including two movable arms, said arms being movable as a unit during normalcperation, a temperature-responsive element for moving said arms, a switch actuated by the-movement of one of said arms,

means engaging the other of said arms for opposing movement of said arms, said means being adjustable for varyingthe temperature at which said'switch is actuated, means for limiting the movement of said other of said arms under predetermined conditions, and a spring for opposing relative movement of said arms whereby movement of said one of said arms for actuating said switch is opposed by said springun'der said predetermined conditions.

I 6. A refrigerator control comprising a switchactuating structure, a switch actuated thereby, said switch-actuating structure including two parallel arms, one of said arms includinga porticn for actuating said switch, a temperatureresponsive element engaging said one of said arms for effecting movement of said arms, an adjustable first spring engaging the other of said arms for biasing said switch-actuating structure, a second spring disposed between said arms and engaging said arms for biasing said arms against relative movement, and a stop for engaging said other of said arms under predetermined conditions for limiting movement of said other of said arms and rendering said first spring ineffective whereby the movement of said one of said arms for actuating said switch under said predetermined conditions is opposed by the bias of said second spring only.

7. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first pivoted arm connected to said switch, a second parallel pivoted arm, a first spring between said arms and enaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for effecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, and a stop for engaging said second arm for limiting movement thereof whereby said second spring is rendered ineffective and subsequent movement of said first arm is opposed only by said first spring.

8. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first pivoted arm connected to said switch, a second parallel pivoted arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for effecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, means for adjusting said second spring, to vary the bias exerted thereby, and a stop for engaging said second arm to limit movement thereof whereby said second spring is rendered ineffective and subsequent movement of said first arm is opposed only by said first spring.

9. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first pivoted arm connected to said switch, a second parallel pivoted arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for efiecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, a rotatable member, said rotatable member having a projection thereon for engaging said second arm, and means for rotating said member to position said projection in line with said second arm for limiting the movement of said second arm whereby said second spring is rendered ineffective and subsequent movement of said first arm is op posed only by said first spring.

10. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first pivoted arm connected to said switch, a second arm pivoted on said first arm and extending parallel thereto, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-respon sive element engaging said first arm for effecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, and a stop for engaging said second arm to limit movement thereof whereby said second spring is rendered ineffective and subsequent movement of said first arm is opposed only by said first spring.

11. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first pivoted arm connected to said switch, a second parallel pivoted arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a stop for limiting the movement of said arms away from each other, a temperature-responsive element engagsaid first arm for effecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, and a second stop for engaging said second arm to limit movement thereof whereby said second spring is rendered ineffective and subsequent movement of said first arm is opposed only by said first spring.

12. A refrigerator control comprising a switch mechanism for actuating said switch, said mechanism including a first movable arm, a second movable arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for effecting movement ther of, a second spring engaging said second arm for biasing said arms during normal operat' a first stop for engaging said second arm to 1 mi movement thereof whereby said second spring rendered ineffective and subsequent movement of said first arm is opposed only by said first spring, a switch member having a movable contact thereon, an overcenter spring between said first arm and said switch member, and a second stop for normally limiting movement of said switch member in the open position of said switch whereby said overcenter spring is moved over center to close said switch before en agement of said first stop by said second arm, said second stop being movable to afford increased movement of said switch member in its open position during defrosting whereby increased movement of said first arm is required for moving said overcenter spring over center to close said switch, said increased movement of said first arm first effecting engagement of said first stop by said second arm and thereafter being opposed only by said first spring.

13. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including two movable arms, said arms being movable as a unit during normal operation, a temperature-responsive element for moving said arms, a switch actuated by movement of on of said arms, means engaging the other of said for opposing movement of said arms, said means being adjustable for varying the temperature at which said switch is actuated, a first stop for limiting the movement of said other of said arms under predetermined conditions, a first spring for opposing relative movement of said arms whereby movement of said one of said arms for actuating said switch is opposed by said spring under said predetermined conditions, said switch including a switch member having a movable contact thereon, an overcenter spring between said one of said arms and said switch member, a second stop for normally limiting movement of said switch member in the open position of said switch whereby said over-center spring is moved over center to close said switch before engagement of said first stop by said other of said arms, said second stop being movable to afford increased movement of said switch member in its open position during defrosting whereby increased movement of said one of said arms is required for moving said overcenter spring over center to close said switch, said increased movement of said one of said arms first efiecting engagement of said first stop by said other of said arms and thereafter being opposed only by said first spring.

14. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first movable arm, a second movable arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for efiecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, a stop for engaging said second arm to limit movement thereof whereby said second spring is rendered ineffective and subsequent movement of said first arm is opposed only by said first spring, a switch member having a movable contact thereon, an overcenter spring between said first arm and said switch member, a cam adapted to cocupy one position for normally limiting movement of said switch member in the open position of said switch whereby said overcenter spring is moved over center to close said switch before engagement of said stop by said second arm, said cam being movable to asecondposition for affording increased movement of said switch member in its open position during defrosting whereby increased movement of said first arm is re- L quired for moving said overcenter spring over center to close said switch, said increased movement of said first arm first effecting engagement of said stop by said second arm and thereafter beingopposed only by said first spring.

15. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first movable arm, a second movable arm, a first spring between said arms and engaging saidjarms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for effecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, a stop for engaging saidsecond arm to limit movement thereof whereby said second spring is rendered inefiective and subsequent movement of said first arm is opposed only by said first spring, a. switch member having a movable contact thereon, an overcenter spring between said first arm and said switch member,'a rotatable disk, the periphery of said disc being engaged by said switch arm in the open position of said switch for normally limiting movement of said switch arm whereby said overcenter spring is moved over center to close said switch before engagement of said stop by said second arm, said disk having a recess in the periphery thereof, said disk being movable to a position wherein said recess is aligned with said switch 'member to afford increased movement of said switch member in its open position during defrosting whereby increased movement of said first arm is required for moving said overcenter spring over center to close said switch, said increased movement of said first arm first efiecting engagement of said stop by said second arm and thereafter being opposed only by said first spring.

16. A refrigerator control comprising a switch and mechanism for actuating said switch, said mechanism including a first movable arm, a second movable arm, a first spring between said arms and engaging said arms for biasing said arms against relative movement toward each other, a temperature-responsive element engaging said first arm for efiecting movement thereof, a second spring engaging said second arm for biasing said arms during normal operation, a stop for engaging said second arm to limit movement thereof whereby said second spring is rendered ineifective and subsequent movement of said first arm is opposed only by said first spring, a switch member having a movable contact thereon, an overcenter spring between said first arm and said switch member, a rotatable disk, the periphery of said disk being engaged by said switch arm in the open position of said switch for normally limiting movement of said switch arm whereby said overcenter spring is moved over center to close said switch before engagement of said stop by said second arm, said disk having a recess in the periphery thereof, means for rotating said disk to a position wherein said recess is aligned with said switch member to afford' increased movement of said switch member in its open position during defrosting whereby increased movement of said first arm is required for moving said overcenter spring over center to close said switch, said increased movement of said first arm first effecting engagement of said stop by said second arm and thereafter being opposed only by said first spring.

CHARLES S. GRIMSHAW.

Name Date Raney Nov. 22, 1938 Number 

